Adding Texture and TriangleMesh Capabilities

* Texture Mapping for GeometricObjects via GeometricObject.getColor();
* Adding Texture to the Material class via Material.getColor();
* Updating Shaders so they now use GeometricObject.getColor(), instead of Material.getColor(), so they can apply illumination over textures;
* Adding Spherical Texture Mapping to the Sphere class;
* Creating the TriangleMesh and PlyReader, to load and render TriangleMeshes from PLY files;
Adding Textures to default Materials
Adding Examples of loading meshes from PLY files
Adding Earth example, for texturing Spheres
Merge branch 'master' of github.com:raphaelpaiva/JTrace

Conflicts:
	src/model/org/jtrace/geometry/GeometricObject.java
	src/model/org/jtrace/geometry/Sphere.java
	src/model/org/jtrace/geometry/Triangle.java
Adding TriangleMesh.sections(), still needs implementation
Adding an example of applying texture to a TriangleMesh